A switch fabric provides pathways for conveying data traffic between external input and output ports. A switch fabric may include an input and an output stage, each stage including a plurality of switching elements. The input and output stages respectively provide a plurality of external input and output ports connected to external connections. The switch fabric also includes one or more intermediate stages including a plurality of switching elements. Internal pathways are selectively established in the switch fabric between the external input ports and the external output ports to provide the switching capability. When the number of external input and output ports is large, it is usually not cost-effective, or technically feasible, to directly connect each external input port to all the external output ports.
One problem that may arise in a switch fabric of the type described above is that the switch fabric may become blocked. The switch fabric is said to be blocked when no pathway between an external input port and an external output port can be established. Therefore, data traffic between these external ports cannot be passed.
Against this background, there exists a need to provide novel techniques to allocate pathways in the switch fabric to reduce the possibility of blocking the switch fabric.